How can I find the Galois group of $(x^2-2)(x^3+x+1)$?
I read the answer to this question for techniques but I didn't find anything about the product of two polynomials.
For the first factor the group is clearly $Z_{2}$, but I can't see it for the second one (how does it help that it has exactly one real root?). Is it generally true that the product of two irreducibles has a Galois group that is the direct sum of the factors?